1. Field of the Invention
The invention is directed to a self-cleaning rotary screen through which cooling air is drawn for cooling an internal combustion engine on an agricultural combine.
2. Description of the Prior Art
In recent years, it has become common practice to enclose the engines of self-propelled agricultural combines. Typically, these enclosures are provided with self-cleaning rotary screens through which a cooling air stream is drawn. Heat exchangers are located behind the screen and include the radiator for cooling the engine, the oil cooler, and the condenser coils for the air conditioning. The screen is used to remove chaff and leaves from the cooling air stream so that they do not block the various heat exchangers located behind the screen.
It is desirable that the screen be automatically and continuously self cleaning to facilitate air flow through the screen. One method of accomplishing this task is to rotate the screen through a stationary chamber which is used to vacuum the trash accumulated on the screen. This stationary chamber maybe pneumatically coupled to the cooling air stream downstream of heat exchangers for reintroducing the trash collected off the screen into the air stream.
The screen maybe operatively coupled to a driving sheave of the propulsion means of the combine, by an endless belt that encircles a flange on the screen. Typically the screen is provided with a central hub on which it is rotated which also serves as a mounting point for the stationary chamber. In this way, the screen is continually and automatically rotated while the engine is operating.
In addition, the screen may be mounted to a pivotable door which can be opened to access the heat exchangers. To open the door, the endless belt must be declutched or disengaged from the driving sheave before the door can be opened. Such a rotary self-cleaning screen and the declutching assembly as described above, are disclosed in U.S. Pat. Nos. 3,837,149 and 4,233,040, both assigned to the assignee of the present application.